I take bets that it has something to do with the signal wiring form the AoA vane to the flight computer (ADIRU) like shorting out one half of the SIN or COS symmetric signal and creating with that something around a 45 degree/2 offset. If the Ethopian airline FDR does show a similar problem, then there is some latent harness, connector or ADIRU problem which will show up in the other 737 MAX made in a similar timeframe. So if that establishes, the investigation might look into some of the grounded planes build in similar timeframe.